“One of the characteristics of Cappadocia is having plenty of underground cities. It’s known that there are more than a hundred underground settlements in the region and many of them are not open for visits. The underground cities, which are guessed to be used since the Bronze Age, used to be settlements mostly in Byzantine period, doubtless. In this period, increasing invasions forced local residents to build underground cities for protection and religious purposes.
In all of the underground cities there are ventilation chimneys reaching place by place to a depth of 80 and until the underground waters. These chimneys were opened due to meet the need of both ventilation and water. Within the cities that are tepid in winters and cool in summers there are kitchens, cribs, wine houses, depots for cereals, meeting saloons, toilets, shortly every kind of living space necessary for living. Within all the cities there are locking stones which can be opened and closed only from inside against to the threats which may come from outside.”
More at the source: Expanded Concsciousness.com